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Katia G Samper, Sierra C Marker, Pau Bayón, Samantha N MacMillan, Ivan Keresztes, Òscar Palacios, Justin J Wilson
The syntheses of three platinum(II) complexes bearing sulfonamide- ( (E)-2-(4-methylphenylsulfonamido)-2',6'-difluoroazobenzene, HL1) and hydroxy-azo-2,6-difluorobenzene ((E)-2-((2,6-difluorophenyl)diazenyl)phenol, HL2) bidentate ligands is described. These complexes, [Pt(L1)(DMSO)Cl] (1), [Pt(L2)(DMSO)Cl] (2), and [Pt(L2)2] (3), were characterized by multinuclear NMR spectroscopy, mass spectrometry, and X-ray crystallography. Despite bearing azobenzene functional groups, none of the three complexes undergo photoisomerization...
June 17, 2017: Journal of Inorganic Biochemistry
Philipp Weis, Si Wu
Azobenzene-containing macromolecules (azo-macromolecules) such as azobenzene-containing polymers (azopolymers) and azobenzene-functionalized biomacromolecules are photoswitchable macromolecules. Trans-to-cis photoisomerization in conventional azo-macromolecules is induced by ultraviolet (UV) light. However, UV light cannot penetrate deeply into issue and has a very small fraction in sunlight. Therefore, conventional azo-macromolecules are problematic for biomedical and solar-energy-related applications. In this Feature Article, the strategies for constructing visible and near-infrared (NIR) light-responsive azo-macromolecules are reviewed, and the potential applications of visible- and NIR-light-responsive azo-macromolecules in biomedicine and solar energy conversion are highlighted...
June 23, 2017: Macromolecular Rapid Communications
Beatriz Blanco, Kathryn A Palasis, Alaknanda Adwal, David F Callen, Andrew D Abell
A series of azobenzene-containing peptidic boronate esters was prepared and the activity of the thermally adapted states (TAS), enriched in trans isomer, and the photostationary states (PSS), enriched in cis isomer, for each compound were evaluated against β5 and β1 proteasome subunits. Compounds with a sterically demanding phenyl-substituted azobenzene at P2 (4c), and a less sterically demanding unsubstituted azobenzene at the N-terminus (5a), showed the greatest difference in activity between the two states...
June 11, 2017: Bioorganic & Medicinal Chemistry
Eva A Jaumann, Sabrina Steinwand, Szabina Klenik, Jörn Plackmeyer, Jan W Bats, Josef Wachtveitl, Thomas F Prisner
Azobenzene compounds are known as versatile examples for photoswitchable systems because of their isomeric cis- and trans-configurations. The switching between these isomers can be reversibly controlled by light excitation. In this study we characterize two members of this class by joining the azobenzene moiety with each two paramagnetic nitroxide spin labels. Two different linkers were chosen to tune the molecular properties. The combined approach using optical and EPR spectroscopy proved the reversibility of photoexcitation and high fatigue resistance...
June 22, 2017: Physical Chemistry Chemical Physics: PCCP
Hubiao Huang, Hiroshi Sato, Takuzo Aida
An azobenzene-containing, zirconium-based metal-organic framework ((Azo)MOF), upon irradiation with ultraviolet (UV) light at 365 ± 10 nm, underwent trans-to-cis isomerization of its azobenzene pendants to furnish the cis-isomer content of 21% ((Azo)MOF(21%)) in 30 min at the photostationary state and underwent backward isomerization into (Azo)MOF(1%) upon either irradiation with visible light (420-480 nm) or heating. When the cis-isomer content increased, the diffusion rate and amount of CO2 adsorbed into the nanochannels of (Azo)MOF decreased considerably...
June 21, 2017: Journal of the American Chemical Society
Alexandre Mourot, Christian Herold, Michael A Kienzler, Richard H Kramer
BACKGROUND AND PURPOSE: We previously developed a photoisomerizable local anaesthetic, named QAQ, to gain rapid, optical control over pain signaling without involving genetic modification. In darkness or in green light, trans-QAQ blocks voltage-gated K(+) and Na(+) channels and silences action potentials in pain-sensing neurons. Upon photoisomerization to cis with near UV light, QAQ blockade is rapidly relieved and neuronal activity is restored. However, the molecular mechanism of cis and trans QAQ blockade is not known...
June 20, 2017: British Journal of Pharmacology
Daniel Hoersch
Azobenzene is a photo-isomerizing molecule whose end-to-end distance changes upon external illumination. When combined with site-specific reactive groups, it can be used as molecular tweezers to remote-control the structure and function of protein targets. The present study gives a brief overview over the rational design strategies that use an azobenzene-based photoswitchable cross-linker to engineer ON/OFF switches into functional proteins or to reprogram proteins for novel functions. The re-engineered proteins may be used as remote controls for cellular pathways, as light-gated drug delivery platforms or as light-powered machinery of synthetic cells and micro-scaled factories...
June 15, 2017: Biochemical Society Transactions
I A Budagovsky, V N Ochkin, S A Shvetsov, A S Zolot'ko, A Yu Bobrovsky, N I Boiko, V P Shibaev
Light-induced director orientation of polymeric liquid-crystalline systems was investigated. The materials under study were composed of a nematic liquid-crystalline polymer (NLCP) and a small amount (0.05-0.5 wt.%) of conformationally active (azobenzene) or stable (anthraquinone) dye impurity. Light action on the homogeneously aligned polymer films above glass transition temperature leads to the director reorientation and, consequently, to a change in the extraordinary refractive index. The effect is associated with the dye molecule excitation and related change of intermolecular forces...
May 2017: Physical Review. E
Guillaume Despras, Julia Hain, Sven Ole Jaeschke
Reversible shape switching upon external stimuli is an attractive property for the control of molecular features. Hence, we aimed at macrocycles to investigate photoswitching of molecular shape. We prepared the first carbohydrate-based macrocycles comprising a photoresponsive azobenzene hinge. These macrocycles were readily obtained by cyclization of isothiocyanate-armed bis-azobenzene glycosides with piperazine. The unprotected macrocycles exhibit favorable photochromic properties in water and DMSO. Notably, the efficient trans→cis isomerization results in a remarkable shape transformation of the molecule...
June 14, 2017: Chemistry: a European Journal
Koji Oohora, Yoshitaka Onuma, Yuta Tanaka, Akira Onoda, Takashi Hayashi
Supramolecular assembly of an engineered hemoprotein with an externally-attached heme moiety via an azobenzene or stilbene linker demonstrates drastic structural transitions between two distinct forms: the thermodynamically stable fiber-type assembly and the kinetically trapped metastable micelle-type assembly induced by transient thermal stimulus.
June 22, 2017: Chemical Communications: Chem Comm
Sergey A Shvetsov, Alexander V Emelyanenko, Natalia I Boiko, Jui-Hsiang Liu, Alexei R Khokhlov
Reversible orientational transitions in the droplets of a nematic liquid crystal (NLC) caused by the change of boundary conditions under the low intensity diode illumination are investigated. Photosensitivity of NLC is achieved by the addition of the dendrimer compound with azobenzene terminal groups. Two types of NLC droplets in glycerol are considered: the spherical droplets in the bulk of glycerol and the droplets laid-down onto the solid substrate. In the second case, the first order phase transition is revealed...
June 7, 2017: Journal of Chemical Physics
Anthony Romieu, Arnaud Chevalier, Pierre-Yves Renard
The use of non-fluorescent azo dyes as dark quenchers in activatable optical bioprobes based on Förster resonance energy transfer (FRET) mechanism and designed to target a wide range of enzymes, has been well established for over two decades. The key value of the azo moiety (-N=N-) to also act as an efficient "ON-OFF" switch of fluorescence once introduced within the core structure of conventional organic-based fluorophores (mainly fluorescent aniline derivatives) has been recently exploited in the developement of alternative reaction-based small-molecule probes based on the "pro-fluorescence" concept...
June 8, 2017: Chemistry, An Asian Journal
M Hendrikx, A P H J Schenning, D J Broer
The light-induced surface topography of a liquid crystal polymer coating is brought into a patterned oscillatory deformation. A dichroic photo-responsive azobenzene is co-aligned with the planar oriented nematic liquid crystal network molecules which makes the surface deformation sensitive to polarized UV light. Locally selective actuation is achieved in coatings with a complex alignment pattern. Dynamic oscillation, as controlled by the actuation and relaxation kinetics of the polymer, is obtained by a continuous change in the polarization of the UV source...
June 21, 2017: Soft Matter
Simona Concilio, Lucia Sessa, Anna Maria Petrone, Amalia Porta, Rosita Diana, Pio Iannelli, Stefano Piotto
Some novel (phenyl-diazenyl)phenols 3a-g were designed and synthesized to be evaluated for their antimicrobial activity. A previously synthesized molecule, active against bacteria and fungi, was used as lead for modifications and optimization of the structure, by introduction/removal or displacement of hydroxyl groups on the azobenzene rings. The aim of this work was to evaluate the consequent changes of the antimicrobial activity and to validate the hypothesis that, for these compounds, a plausible mechanism could involve an interaction with protein receptors, rather than an interaction with membrane...
May 25, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Chavdar Slavov, Chong Yang, Luca Schweighauser, Hermann A Wegner, Andreas Dreuw, Josef Wachtveitl
Azobenzenes are widely utilized as molecular photoswitches for control of nanoscale processes. Their photoisomerization reaction is highly robust and is retained even in extremely rigid systems. Currently, it is not clear what geometric restrictions are required to block this isomerization successfully. We present here a combined experimental and theoretical study on the ultrafast dynamics of cyclotrisazobenzene (CTA) and demonstrate that the structural constraints in CTA prevent isomerization of the photoswitch units...
June 6, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Ruowen Wang, Cheng Jin, Xiaoyan Zhu, Liyi Zhou, Wenjing Xuan, Yuan Liu, Qiaoling Liu, Weihong Tan
In contrast to small molecules, DNA and RNA macromole-cules can be accurately formulated with base "elements" abbreviated as A, T, U, C and G. However, the development of functionally artificial bases can result in the generation of new biomaterials with unique properties and applications. Therefore, we herein report the design and synthesis of a photoresponsive base as a new functional "element" for con-structing DNA nanomolecules. The new base is made by fusion of an azobenzene with a natural T base (zT)...
June 6, 2017: Journal of the American Chemical Society
Xili Lu, Shengwei Guo, Xia Tong, Hesheng Xia, Yue Zhao
A new strategy for enhancing the photoinduced mechanical force is demonstrated using a reprocessable azobenzene-containing liquid crystalline network (LCN). The basic idea is to store mechanical strain energy in the polymer beforehand so that UV light can then be used to generate a mechanical force not only from the direct light to mechanical energy conversion upon the trans-cis photoisomerization of azobenzene mesogens but also from the light-triggered release of the prestored strain energy. It is shown that the two mechanisms can add up to result in unprecedented photoindued mechanical force...
June 6, 2017: Advanced Materials
Laura Laprell, Ivan Tochitsky, Kuldeep Kaur, Michael B Manookin, Marco Stein, David M Barber, Christian Schön, Stylianos Michalakis, Martin Biel, Richard H Kramer, Martin P Sumser, Dirk Trauner, Russell N Van Gelder
Photopharmacological control of neuronal activity using synthetic photochromic ligands, or photoswitches, is a promising approach for restoring visual function in patients suffering from degenerative retinal diseases. Azobenzene photoswitches, such as AAQ and DENAQ, have been shown to restore the responses of retinal ganglion cells to light in mouse models of retinal degeneration but do not recapitulate native retinal signal processing. Here, we describe diethylamino-azo-diethylamino (DAD), a third-generation photoswitch that is capable of restoring retinal ganglion cell light responses to blue or white light...
June 5, 2017: Journal of Clinical Investigation
Manuel Pescher, Luuk van Wilderen, Susanne Gruetzner, Chavdar Slavov, Josef Wachtveitl, Stefan Hecht, Jens Bredenbeck
The azobenzene-containing photoswitchable piperidine general base catalyst is a prototype structure for light control of catalysis. Its azobenzene moiety moves sterically-shielding groups to either protect or expose the active site, thereby changing the compound's basicity and hydrogen-bonding affinity. The catalyst's reversible switching dynamics is probed in the infrared spectral range by monitoring hydrogen-bond formation between its active site and methanol (MeOH) as hydrogen-bond donor. Steady-state infrared (IR) and ultrafast IR and UV/Vis-spectroscopies are used to uncover ultrafast expulsion of MeOH from the active site within a few picoseconds...
June 1, 2017: Angewandte Chemie
Yingxue Hu, Wenyue Zou, Villy Julita, Rajesh Ramanathan, Rico F Tabor, Reece Nixon-Luke, Gary Bryant, Vipul Bansal, Brendan L Wilkinson
Naturally occurring and synthetic carbohydrate amphiphiles have emerged as a promising class of antimicrobial and antiadhesive agents that act through a number of dynamic and often poorly understood mechanisms. In this paper, we provide the first report on the application of azobenzene trans-cis photoisomerization for effecting spatial and temporal control over bacterial growth and biofilm formation using carbohydrate-based surfactants. Photocontrollable surface tension studies and small angle neutron scattering (SANS) revealed the diverse geometries and dimensions of self-assemblies (micelles) made possible through variation of the head group and UV-visible light irradiation...
November 1, 2016: Chemical Science
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